Maximum-demand indicator.



fm. 728,546. v l l Y 'PATDNTDDMAY 19, 1903.

. y F. P. MAXIMUM DEMAND INDICATOR.

APPLIDATIDNHLBD 1mm, labs.

lo MODEL. l

IEIlD y l l Prank I www;

...Ord

flmgf UNITED STATES Patented May 19, A1903. i

PATENT OFFICE. I

FRANK P. COX, OF LYNN, MASSACHUSETTS, ASSIGNOR TO T HE GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

MAXIMUM-DEMAND mulch-FOR.

SPECIFICATION forming part of Letters .Patent N o. 728,546, dated May 19, 1903.

`Application iilerillllarch Z, 1899.

To all whom it may concern,.-

Beit known that I, FRANK P. Cox, a oitizen of the United States, residing atv Lynn, county of Essex, State of Massachusetts, have invented certain new and useful Improvements in! Maximum Demand Indicators, of which the following is a specification.`

This invention relates to means for recording the maximum degree of electric energy 1o which iiows through any multicircuit system,

with especial reference to the three-wire system of distr-ibution, which is so widely in use at the present time. The recording vmeans naturally and essentially executes a method of recording.

The idea of basing rates of charge to consumers of electric energyupon the maximumv rate of flow for an lappreciable time is not novel and many forms of meters for carryzo ing out this idea have been invented. Such meters have been used `with the three-wire system, in which case two maximum-meters have been used, each being connected with one of the outside wires, so that each circuit z 5 would actuate a separate meter.V Each meter was read and the sum of the readings was taken as the maximum rate of current-How.V This has been considered satisfactory for some time and mightbe so considered for 3o some time in the future in spite of'the expense of two meters for a three-'wire system and extra meters in proportion tothe number of circuits. However, I have devised a novel apparatus by which not only is the extra cost of-apparatus entirely unnecessary, but there are prevented certain very serious errors of vthe old method.-v In'the old method the sum of the readings does not in all' cases represent the actual maximum demand or 4: rate of .liow of energy. lIt represents the true rate only when the consumer uses the same number of lamps or other` translating devices on both sides at all times-that is, when the load. is'equallyfbalanced and no current flows in the neutral wire. This is exceptional, especially in the case of a householder, for example, even if an equal num- Y ber of lamps be connected to each side of the system, for the use of these lamps may be 5o varied Very much and independently of the manner in which theyare connected with the Serial No. 707,456. (No model.)

housemains. Forl example, the consumer may one evening have ten lamps operating on one side of the system'aud none on .the

:other meter will'make no record. The next evening he may use ten lamps on the other side of the systeml and none on the first- 6o mentioned side. In this case the maximum-v meter on theother side will record a current of live amperes'and the other meter will `make no further record. The sum of the records of the two meters will be ten amperes; but the consumer has not in either evening exceeded a current of ive amperes fand the discount allowed him will be based ou a maximum demandof one hundred per cent. in excess of the actual demand. This 7o is lan extreme case; but it is clear that a system in which such errors are possible is very, objectionable. n f The improved'method consists in causing the energy flowing through each circuit of the system nto operate a common maximumrecording device. If to the above-described illustrative case this method be applied, it will be seen that the maximum-meter which is common to both sides of thethree-wire 8o system will not make further record on the second evening, but that whenever a larger current than has yet been recorded flows through either circuitialone or both together the meter will record that maximum.

In the accompanying drawings, which illustrate an embodiment of my invention, Figure l isa diagrammatic View of a three-wire system having'a maximum-demand indicator in circuit; and Fig. 2 is also a diagrammatic 9o View of a three-Wire system, but with-a modified form of an'indicator. i

In so far as the operation of my invention is concerned it is immaterial what kind of maximum-indicator is used'so long as it is affected. 95 by the current flowing in both-"sides of the three-Wire system. Neither does it matter whether it is. applied to alternating or direct current systems.

'In the drawings I have shown two types of :oo instruments; but it is evident that other forms may be employed.

The instrument shown in Fig. 1 is illustrated because it is so simple that it most clearly represents the application of the method.

Referring to Fig. l, A and B indicate the two outside wires, and C the neutral wire, of a three-wire system. Extending from these wires are auxiliary or house mains A B' C', which supply energy to the lamps or other translating devices D. The maximum-demand indicator consists of a U-shaped transparent tube E, having an enlargement or bulb K at one end, around which the heating-coils are placed, and an enlargement or bulb L, into which the fluid flows when it is desired to empty the middle tube G. 'lhe bulb K is preferably formed integral with the tube, and surrounding it are two heatingcoils H and I. The former is connected in series with the main A and the latter in series with the main B. The tube E contains an indicating fluid, and the bulb K and that part of tube E between the bulb and the indicating fluid are filled with air or gas. The heating-coils H and I cause the temperature of the bulb to rise and the air or gas contained therein to expand, the expansion being proportional to the current flowing in the heating-coils. This expansion causes a portion of the indicating fluid to flow into the middle tube G, on the sides of which is a suitable scale by means of which readings may be made. The coils and tube are so proportioned and arranged that the momentary impulses of current will not cause the fluid F to overflow into the tube G; but if after a brief interval the current-flow still persists the temperature will rise to a point which causes the fluid in the bulb K to expand and the indicating fluid to flow into the tube.

Owing lo the diculty of making currentcoils develop the same amount of heat for a given flow of. current a resistance J is provided, by means of which more or less of the current may be shunted past one of the 'coils until its heating effect for a given load corresponds to the other coil. The resistance in addition to adjusting the coils with respect to each other performs another useful function, since it is useful for changing the rate of a given consumer. For example, suppose that an'indicator has been installed at a given place where one rate of charge is established and it is desired to change the indicator to a place where a different rate is charged. To accomplish this, it is only necessary to change the amount of resistance shunting the heating-coils H and I, and the indicator will operate as desired.

Assuming that sufficient load is included between the mains A B C' to cause the heating-coils H and I to raise the temperature of the expansive fluid to a point above normal, the indicating fluid will then flow into the tube G and by its amount indicate the maximum demand on the central station. It will be noted that the same effect is obtained whether the load is all on one side or on the other or equally distributed between them.

The invention having been fully described with respect to one form of maximum-meter will now be describedin its application to the metershownin the patent to Fish,No. 631,289, in order toillustrate the statement on page 2, that the invention is not limited in its application to a maximum-meter of any specific construction.

Referring to Fig. 2, A', B, and C indicate, respectively, the outside mains and the neutral of a three-wire system, and D indicates incandescent lamps or other translating devices. In circuit with the auxiliary main A is a coil I-I, and in circuit with the auxiliary main B' is a coil I, and mounted for movement within these coils is an iron armature M. Thus far the arrangement of the coils and needle is the same as in an ordinary ammeter, except that two coils are employed instead of one. Mounted on the shaft of the instrument is a contact-arm N, which engages with a pin O, carried by the pointer O. The pointer O is mounted on a shaft O2, which is driven by a clock of any suitable construction, the one shown being driven by the spring P in the ordinary manner. For convenience of illustration I have shown the spring and the gears of the clock in dotted lines. Mounted on the shaft which carries the escapement-is an arm Q, which engages with a magnetically-actuated lever' Q'. Situated in operative relation to this lever is an electromagnet R, and the winding thereon is connected between the outside main B and the contact-arm N. Extending from the neutral wire C' to the pointer O is a connection S.

The operation will now be described: As

-the lamps or other translating devices are ineluded in circuit with either or both sides of the system, the armature M is deflected and if this deflection is sufficient the contact-arm N is moved into engagement with the pin O'. As soon as this is done the circuitis complete from the main B through the contact-arm N, pointer O, and Wire S to the neutral wire C. This attracts the armature of lever Q and releases the escapement-lever Q and the clock begins to run. This operation continues until the pin O' on the pointer moves out of engagement with the contact-arm N. As soon as this is done the circuit of the energizing coil or magnet R is interrupted, the lever Q assumes the position shown in the drawings due to gravity, and further movement of the escapement is prevented. The construction and arrangement of the parts are such that the pointer O can be moved forward by the clock mechanism over the scale T, (seen in dotted IOO IIO

lines,) but it remains in its last position until three-wire systems, the combination of an indicatingmeans which is moved by the action of the current flowing in the system and is incapable of. automatically returning to its initial position, and means controlled by the current Iiowing in both sides of the system for actuating the indicator. y

2. In a maximum-demand instrument for use on systems of distribution other than two- Wire, the combination of indicating means, which, as an indicator of the consumption of energy is capable of being moved in one direction only from its initial position, and means controlled by the load on morethan one of the mains for moving the indicating means. f v

3. In a maximum-demand instrument for use on systems of distribution other than two- Wire, the combination of indicating means which is capable of being moved in one direction only by the current flowing in the system, and always remains in the position of maximum even after the iiow of current decreases,

and coils which receive energy from at least two of the mains for actuating the indicating means.

4. In a maximum-demand instrument foruse on three-wire systems, the combination vof indicating means which is moved from its initial position by the energy consumed by the translating device in the circuit and is normally prevented from returning to its initial position, with coils, one in each of the outside mains of the system, for moving the indicating means.

5. In a maximum-demand instrument, the combination of indicating means which has no self-returning tendency but is moved away from its initial position by the action of the current in the system, and as the oW of current increases assumes a new position in accordance therewith, a plurality of coils for moving the indicating means and means for adjusting the power of the coils.

6. In a maximum-demand.l instrument for three-wire systems,the combination of a tube, a body of expansible fluid located therein which acts as an indicator, a coil included in circuit with each of the outside mains for heating the fluid, the two coils acting simultaneously and with an effect corresponding to the current flowing in the main in which they are located.

7. In a maximum-demand instrument for three-wire systems the combination of indicating means which is moved by increases in current strength, and by its. position indi- Cates the maximum demand on the central station, the indicating means always standing at the point of maximum demand irrespective of the amount of current being consumed at that time, heating-coils for moving the indieating means each coil being included in one of the outside mains of the system, and shunts for adjusting the effect of the coils.

8. The combination with a single device which is constructed and arranged to record the maximum flow of current, of means whereby the device is affected by the dierent circuits of a m-ulticircuit system.

9. A single instrument, which is provided with indicating means, which, after it has been moved, cannot return to its initial position, and is caused to be moved whenever the degree of energy flowing through a multicircuit system is greater than that which has previously flowed through the system.

l0. A single instrument which is provided with indicating means, which, after it has been moved, cannot return to its initial position, and a plurality ofl coils, each. of which operates the said indicating means, and each of which is connected with one circuit of a multicircuit system.

11. A single instrument which comprises indicating means, which, afterit has been moved, cannot return to its initial position, a.

plurality of coils, each of which operates said indicating means,and each of which is connected with a different circuit of a multicircuit system, andan adjustable resistance in each circuit .in shunt to the coil.

12. A single instrument which records the maximum degree of electric energy which ows through a multicircuit system, and is 9 provided with means for changing the rate of recording. l

13. A single instrument which records the maximum degree of elect-ric energy which flows through a multicircuit system, and is provided with means for causing any current in any circuit to make the same record as an` equal current in any other circuit. Y

14. A single instrument which comprises a plurality of coils, each of which is connected with a different circuit in the multicircuit system, and a part which is movable in only one direction by one of said coils or by any number thereof cooperatively.

In witness whereof I have hereunto set my hand this 27th day of February, 1899.

FRANK P. COX.

Witnesses:

DUGALD McKILLoP, HENRY O. WESTENDARP.

IOO 

